Technical Field
The present invention relates to an alarm device, and more particularly, to an alarm device for feedthrough assembly and alarm method thereof.
Description of Related Art
To allow the feedthrough assembly being operated safely and consistently under the required conditions, the feedthrough assembly requires shaft seal to prevent leakage of the lubricant within the assembly, and to prevent external dust, moisture, foreign substances, liquids, gases and other substances from entering into the feedthrough assembly. The assembly for such purpose is the feedthrough assembly.
Magnetic Fluid, made of magnetic particles, surfactants and base carrier liquid, is mostly used as the medium in shaft seal of feedthroughs. Magnetic particles, nano-ferromagnetic molecular covered by base carrier liquid, will form into different kinds of shapes distributed along with magnetic lines of flux when affected by externally magnetic field, which enables magnetic fluid to formulate an enclosed environment, such that the external magnetic field and inserted magnetic fluid will formulate a barrier between the tiny gap. Thus, the implementation of magnetic fluid seal separates the internal part into two compartments.
Some procedures requires vacuum environment. The inner body with installed shaft seal used with ferrofluid can form an enclosed space and then, by using the vacuum suction pump, it creates a vacuum. Normally, the ferrofluid can tolerate the pressure difference between inner vacuum and the external environment.
Magnetic fluid, or ferrofluid, used as the shaft seal in the feedthrough assembly, is featured for its tightness, no solid friction loss, no pollution produced from seal material abrasion powder, no high temperature and noise induced from contact friction. Moreover, it has longer life and easy for maintenance. Above all, ferrofluid shaft seal is best recommended for all kinds of accurate environmental sealing system.
As technology advances, the shaft seal used with ferrofluid requires higher quality which can meet the sealing standard under strict conditions and also maintain sealing with the shaft in relative movement. All kinds of feedthrough assembly become consequential.
Feedthrough assembly with ferrofluid shaft seal can be applied in different tough working environments, though, it has limitations. For example, the carrier liquid of magnetic fluid will easily evaporate because of high steam pressure, which leads to life shortening or weakening of operation under extreme conditions of the sealing device. Other than that, higher working temperature accelerates the evaporation of the carrier liquid or demagnetization or decreased strength of the magnets, which means reducing the tightness of the sealing. Generally, the proper temperature of working environment should be less than 80 degrees Celsius for magnetic fluid seal device.
Many reasons are known to affect the efficacy of ferrofluid shaft seal, such as overheat of the shaft seal, solid deposition obstruction, high activity gas invasion or degradation failure of the device, etc. The failure of shaft seal will cause abnormalities, and thus, it is necessary to arrange regular test for the shaft seal, in case of crisis which leads to much more losses. Conventionally, the position of malfunction can be detected through the Helium leak detector, which spends a lot of time to check each shat seal of failure among the whole body. If the shaft seal is finally detected after all failure, it is usually too late to change machine. Generally, time consumption of conventional detection is large and it causes great losses.